SRF301 - Comparison of Bone-Conduction Cervical VEMPs Between Infants and Young Adults

Abstract:
The cervical vestibular evoked myogenic potential (cVEMP) has become a routine component of the objective vestibular test battery. More recently, the bone conduction cVEMP (BC-cVEMP) has been used for vestibular screening in infants with sensorineural hearing loss at risk for vestibular impairment. However, our understanding of cVEMPs is primarily based on responses collected in adults. Few studies have described BC-cVEMP response characteristics in infants. The purpose of the current study is to characterize BC-cVEMPs in 3-6-month-old infants and compare them to responses collected from young adults. This information will guide our interpretation of typical and atypical infant cVEMP responses.

Summary::
The cervical vestibular evoked myogenic potential (cVEMP) is an objective vestibular test that can be reliably performed in infants under the age of 6 months (Martens et al., 2023). cVEMPs measure the integrity of the saccule, inferior vestibular nerve, and descending pathway to the ipsilateral sternocleidomastoid muscle (SCM).  Recently, bone conduction cVEMPs (BC-cVEMPs) was implemented as a vestibular screening measure for infants with sensorineural hearing loss by Martens et al. (2022). However, few studies have characterized BC-cVEMPs in infants without sensorineural hearing loss. The purpose of this study is to characterize BC-cVEMPs in a group of 3–6-month-old infants and compare responses to a group of healthy, young adults.

Hypotheses:
1) Infants without sensorineural hearing loss will have comparable P1 and N1 latencies, raw and corrected peak-to-peak amplitudes, and raw EMG amplitude to young adults.
2) There will be no significant difference in the overall BC-cVEMP response rate between infants and adults.

Methods:
BC-cVEMPs from a group of 3-6-month-old infants without sensorineural hearing loss (M = 4.5 months; 3 male) were compared to a group of young, healthy adults (M = 23.4 years; 5 female). BC-cVEMPs were recorded using a 500 Hz tone burst delivered at 62 dB nHL (129 dB peak force level). Recordings were made from the side ipsilateral to the stimulated ear. BC-cVEMPs were recorded and labeled for P1 and N1 latencies, raw and corrected peak-to-peak amplitude, and raw EMG amplitude. An independent samples t-test was used to determine group differences in response parameters between the infants and adults. Non-parametric tests were performed where indicated. A chi-squared test was used to determine significant differences in response rate between infants and adults.

Results:
Data collection is ongoing. However, preliminary results have revealed that BC-cVEMPs are present bilaterally in 100% of adults (5/5) and 83% of infants (5/6). There is no significant difference in BC-cVEMP response rate between infants and young adults. Additionally, results are trending toward earlier P1 latency and smaller raw and corrected peak-to-peak amplitudes in infants.  No significant differences in raw EMG amplitude, N1 latency, and P1-N1 latency have been observed.

Discussion and

Conclusions:
BC-cVEMPs can be reliably measured in young infants, and information obtained from this study will be valuable for enhancing our understanding of vestibular responses in infants compared to adults. Should these trends continue, these findings may also be helpful for considering the feasibility of implementing the BC-cVEMP as an infant vestibular screening measure, as well as guiding our understanding and interpretation of atypical responses.

Learning Objectives:

• Describe typical response characteristics of BC-cVEMP in 3–6-month-old infants
• Define a protocol for accurate BC-cVEMP recordings in infants
• Describe limitations of the infant cVEMP and challenges for recording the cVEMP in infants